Supplementation Lowers Blood Pressure Research Articles

Beetroot Supplementation Lowers Blood Pressure, But Does Not Improve Exercise Efficiency In Female Masters Swimmers

Beetroot supplements are high in dietary nitrate, which increases nitric oxide (NO) in the blood circulation. While NO can lower blood pressure and reduce the oxygen cost of exercise, this has mainly been studied in male athletes. Less is known about the effects of BRS in female athletes, especially swimmers. PURPOSE: To determine if acute beetroot supplementation (BRS) lowers blood pressure (BP) and improves exercise efficiency in female masters swimmers during treadmill exercise. METHODS: 11 swimmers (57.8±10.5 y) underwent 2 randomized, double-blinded trials and ingested beetroot supplement (BE) or placebo (PL). BP, heart rate (HR), and NO response, determined indirectly via changes in salivary nitrite (NO2-), was measured pre-ingestion (Base), pre-exercise (Pre), and 5 min post-exercise (Post). Oxygen consumption (VO2), HR, and rating of perceived exertion (RPE) were measured during the modified Balke test until HR reached 85% of age-predicted maximum. Changes in salivary NO2- were determined using NO2- detection strips and quantified as percentage of reference standard. 2-way repeated measures ANOVA was used to determine differences in BP, HR and salivary NO2-. Peak VO2, treadmill time, and peak RPE were analyzed by 2-tailed t-tests. RESULTS: Salivary NO2- increased from Base to Post in BE compared to PL (32.5 ± 7.0 vs 2.7 ± 3.9%, p=0.001). No treatment differences existed for peak VO2 (BE: 29.3 ± 2.0 vs PL: 29.7 ± 2.7 ml·kg-1·min-1, p=0.31), treadmill time (BE: 15.5 ± 1.9 vs PL: 15.4 ± 1.8 min, p=0.92), or peak RPE (BE: 6.2 ± 0.5 vs PL: 6.5 ± 0.5, p=0.26). Diastolic BP was significantly lower in BE vs PL, respectively (Base: 74.6 ± 1.7 vs 73.2 ± 2.3, Pre: 73.6 ± 1.8 vs 74.5 ± 2.1, Post: 74.5 ± 1.7 vs 76.1 ± 2.2 mmHg, p=0.03, treatment x time), while systolic BP changes trended towards significance in BE vs PL (Base: 116.6 ± 1.5 vs 115.5 ± 1.6, Pre: 115.0 ± 1.7 vs 116.0 ± 1.7, Post: 116.5 ± 1.4 vs. 118.3 ± 1.5 mmHg, p=0.053). HR at Base, Pre, and Post was not different in BE vs PL (62.0 ± 2.4, 63.2 ± 2.5, and 72.6 ± 3.2 vs 63.6 ± 2.1, 65.4 ± 2.2, and 74.6 ± 2.4 bpm, p=0.86). CONCLUSIONS: Acute BRS lowers diastolic BP, but does not improve exercise efficiency in this group of trained, normotensive female masters swimmers. More research is needed in other female masters athlete groups such as runners and cyclists, and in female athletes with hypertension.

Randomised, double-blind, placebo-controlled clinical trial investigating the effects of inorganic nitrate in hypertension-induced target organ damage: protocol of the NITRATE-TOD study in the UK

IntroductionArterial stiffness and left ventricular (LV) hypertrophy are the key markers of hypertensive target organ damage (TOD) associated with increased cardiovascular morbidity and mortality. We have previously shown that dietary...

Does ginger supplementation lower blood pressure? A systematic review and meta-analysis of clinical trials.

The aim of the present systematic review and meta-analysis was to determine the efficacy of ginger supplementation on blood pressure (BP). PubMed, Scopus, ISI Web of Science, Cochrane Library, and Google Scholar were comprehensively searched until September 2018. Human clinical trials, which reported the effect of ginger supplementation on aortic and/or brachial BP, were included. Mean differences were pooled using a random effects model. Standard methods were used for assessment of heterogeneity, sensitivity analysis, and publication bias. Total of six randomized clinical trials (345 participants) were included in the meta-analysis. Pooled analysis suggested that ginger supplementation can reduced systolic BP (MD: -6.36mmHg, 95% confidence interval [-11.27, -1.46]; I2 =89.8%; P=.011) and diastolic BP (MD: -2.12mmHg, 95% confidence interval [-3.92, -0.31]; I2 =73.4%; P=.002). When studies were categorized based on participants' mean age, ginger dosage and duration of intervention, systolic BP and diastolic BP were significantly decreased only in the subset of studies with mean age≤50years, follow-up duration of ≤8weeks and ginger doses ≥3g/d. Our findings revealed that ginger supplementation has favorable effects on BP. Nonetheless, further studies are warranted before definitive conclusions may be reached.

L-arginine supplementation lowers blood pressure, protein excretion and plasma lipid profile in experimental salt-induced hypertension in pregnancy: Relevance to preeclampsia

This study aimed to investigate the effects of L-arginine supplementation on blood pressure, protein excretion, lipid profile in salt-induced hypertensive pregnant rats.Female Sprague-Dawley rats were divided into 4 groups. Control Preg (normal rat chow). Control Preg + L-ARG (normal rat chow and daily oral L-Arginine from 16th – 20th week). Salt Preg (high salt diet, 8%). Salt Preg + L-ARG (high salt diet, 8% and daily oral L-Arginine from 16th – 20th week. Non-invasive BP was recorded using a tail-cuff machine at 1 st and 2nd trimesters. On day 19 of pregnancy, invasive BP was obtained by carotid artery cannulation connected to LabChart-7 pro software. This was followed by blood samples collection for lipid profile analysis.L-arginine significantly reduced (P < 0.05) systolic, diastolic, MAP at 1 st, 2nd trimesters, day 19 of pregnancy, LDL, plasma and urinary creatinine and protein levels in Control Preg + L-ARG and Salt Preg + L-ARG groups compared to other groups. Urinary Na + and K + were significantly higher (P < 0.05) in Salt Preg + L-ARG group compared to other groups. Total cholesterol level was significantly higher (P < 0.05) in salt groups compared to control groups. Triglyceride level and urine volume were significantly higher (P < 0.05) in Salt Preg group compared to other groups. It also significantly increased (P < 0.05) HDL in Control Preg + L-ARG and Salt Preg + L-ARG groups compared to other groups. L-arginine supplementation ameliorates some deleterious effects in salt- induced hypertensive pregnant rats possibly through its known NO vasodilatory effect and might also mediate a diuretic like action.

Correction to: Inorganic Nitrate Supplementation Lowers Blood Pressure in Humans: Role for Nitrite-Derived NO.

Correction to: Inorganic Nitrate Supplementation Lowers Blood Pressure in Humans: Role for Nitrite-Derived NO In the article by Kapil et al, “Inorganic Nitrate Supplementation Lowers Blood Pressure in Humans: Role …

Taurine Supplementation Lowers Blood Pressure and Improves Vascular Function in Prehypertension: Randomized, Double-Blind, Placebo-Controlled Study.

Taurine, the most abundant, semiessential, sulfur-containing amino acid, is well known to lower blood pressure (BP) in hypertensive animal models. However, no rigorous clinical trial has validated whether this beneficial effect of taurine occurs in human hypertension or prehypertension, a key stage in the development of hypertension. In this randomized, double-blind, placebo-controlled study, we assessed the effects of taurine intervention on BP and vascular function in prehypertension. We randomly assigned 120 eligible prehypertensive individuals to receive either taurine supplementation (1.6 g per day) or a placebo for 12 weeks. Taurine supplementation significantly decreased the clinic and 24-hour ambulatory BPs, especially in those with high-normal BP. Mean clinic systolic BP reduction for taurine/placebo was 7.2/2.6 mm Hg, and diastolic BP was 4.7/1.3 mm Hg. Mean ambulatory systolic BP reduction for taurine/placebo was 3.8/0.3 mm Hg, and diastolic BP was 3.5/0.6 mm Hg. In addition, taurine supplementation significantly improved endothelium-dependent and endothelium-independent vasodilation and increased plasma H2S and taurine concentrations. Furthermore, changes in BP were negatively correlated with both the plasma H2S and taurine levels in taurine-treated prehypertensive individuals. To further elucidate the hypotensive mechanism, experimental studies were performed both in vivo and in vitro. The results showed that taurine treatment upregulated the expression of hydrogen sulfide-synthesizing enzymes and reduced agonist-induced vascular reactivity through the inhibition of transient receptor potential channel subtype 3-mediated calcium influx in human and mouse mesenteric arteries. In conclusion, the antihypertensive effect of chronic taurine supplementation shows promise in the treatment of prehypertension through improvement of vascular function.

Abstract MP24: Urinary Potassium Excretion and Risk of Developing Hypertension

Background: Potassium supplementation lowers blood pressure (BP) in randomized controlled trials, but the long-term effect of dietary potassium intake on risk of hypertension has not yet been established. Objective: To examine the association of 24h urinary excretions of potassium, reflecting dietary uptake, with risk of hypertension. Methods: We used data from the Prevention of Renal and Vascular End-Stage Disease (PREVEND) study, a prospective, community-based, observational cohort of Dutch men and women aged 28-75 years. Potassium excretion was measured at baseline (1997-98) and during follow-up (2001-03) in two consecutive 24h urine specimens. Risk of hypertension (defined as BP ≥140/90 mmHg, or initiation of BP-lowering drugs) was studied in 5,511 normotensive subjects not using BP-lowering drugs at baseline. We used Cox proportional hazards regression analysis with time-dependent covariates. Results: Baseline median potassium excretion was 72 mmol/24h (Q1-Q3: 57-85 mmol/24h). During a median follow-up of 7.6 years (Q1-Q3: 5.0-9.3 years), 1172 subjects developed hypertension. We observed a nonlinear association between potassium excretion and risk of hypertension (P=0.005; Figure ). This association was in such a way that the lowest sex-specific tertile of potassium excretion (men: &lt;68 mmol/24h; women: &lt;58 mmol/24h) had an increased risk of hypertension (hazard ratio [HR], 1.22; 95% confidence interval [CI], 1.08-1.37) after adjustment for age and sex, compared to the upper two tertiles. Further adjustment for body mass index, smoking status, alcohol intake, parental history of hypertension (HR, 1.25; 95% CI, 1.11-1.41), and additionally for 24h urinary excretions of sodium, magnesium, and calcium (HR, 1.23; 95% CI, 1.08-1.40) did not materially affect the association. Conclusions: In this population-based cohort, low potassium excretion was associated with an increased risk of developing hypertension. Figure: Association between 24h urinary potassium excretion and risk of hypertension.

Cholecalciferol Treatment to Reduce Blood Pressure in Older Patients With Isolated Systolic Hypertension

Observational data link low 25-hydroxyvitamin D levels to both prevalent blood pressure and incident hypertension. No clinical trial has yet examined the effect of vitamin D supplementation in isolated systolic hypertension, the most common pattern of hypertension in older people. To test whether high-dose, intermittent cholecalciferol supplementation lowers blood pressure in older patients with isolated systolic hypertension. Parallel group, double-blind, placebo-controlled randomized trial. Primary care clinics and hospital clinics. Patients 70 years and older with isolated systolic hypertension (supine systolic blood pressure >140 mm Hg and supine diastolic blood pressure <90 mm Hg) and baseline 25-hydroxyvitamin D levels less than 30 ng/mL were randomized into the trial from June 1, 2009, through May 31, 2011. A total of 100,000 U of oral cholecalciferol or matching placebo every 3 months for 1 year. Difference in office blood pressure, 24-hour blood pressure, arterial stiffness, endothelial function, cholesterol level, insulin resistance, and b-type natriuretic peptide level during 12 months. A total of 159 participants were randomized (mean age, 77 years). Mean baseline office systolic blood pressure was 163/78 mm Hg. Mean baseline 25-hydroxyvitamin D level was 18 ng/mL. 25-Hydroxyvitamin D levels increased in the treatment group compared with the placebo group (+8 ng/mL at 1 year, P < .001). No significant treatment effect was seen for mean (95% CI) office blood pressure (−1 [−6 to 4]/−2 [−4 to 1] mm Hg at 3 months and 1 [−2 to 4]/0 [−2 to 2] mm Hg overall treatment effect). No significant treatment effect was evident for any of the secondary outcomes (24-hour blood pressure, arterial stiffness, endothelial function, cholesterol level, glucose level, and walking distance). There was no excess of adverse events in the treatment group, and the total number of falls was nonsignificantly lower in the group receiving vitamin D (36 vs 46, P = .24). Vitamin D supplementation did not improve blood pressure or markers of vascular health in older patients with isolated systolic hypertension. isrctn.org Identifier: ISRCTN92186858.

Reply to “Letter to the Editor: ‘How does potassium supplementation lower blood pressure?’”

to the editor: We appreciate Dr. McDonough's and Dr. Nguyen's valuable comments and interest (6a) in our study. They raised several interesting issues regarding our recent paper ([4][1]), which explored the molecular mechanisms responsible for the blood pressure-lowering effect of potassium

How does potassium supplementation lower blood pressure?

to the editor: Hypertension is one of the most common diseases in the United States, not easily controlled with medication, and its sequelae are among the most common causes of mortality. Interestingly, hypertension is found mainly in industrialized societies, with very low prevalence in isolated

Protein supplementation lowers blood pressure in overweight adults: effect of dietary proteins on blood pressure (PROPRES), a randomized trial

Dietary protein intake may help to manage blood pressure (BP) and prevent complications associated with elevated BP. The objective of this study was to determine whether 4 wk of increased protein intake (∼25% compared with ∼15% of energy intake that isoenergetically replaces carbohydrate intake) lowers office and daytime BP compared with increased carbohydrate intake. A randomized, double-blind, parallel study compared consumption of 3 × 20 g protein/d (20% pea, 20% soy, 30% egg, and 30% milk-protein isolate) with 3 × 20 g maltodextrin/d. Protein or maltodextrin were isoenergetically substituted for a sugar-sweetened drink. Primary outcomes were office and daytime BP. A total of 99 men and women [age range: 20-70 y; BMI (in kg/m²): 25-35] with untreated elevated BP (BP ≥130/85 and <160/100 mm Hg) were randomly assigned. Ninety-four completers (51 subjects in the maltodextrin group, 43 subjects in the protein group) were included in the analyses. Office systolic blood pressure (SBP) and diastolic blood pressure (DBP) were 4.9 ± 1.7 mm Hg (P = 0.005) and 2.7 ± 1.3 mm Hg (P = 0.05) lower, respectively, in the protein group. Daytime SBP was 4.6 ± 1.7 mm Hg lower in the protein group (P = 0.006), whereas daytime DBP did not differ between groups (P = 0.37). Urinary sodium excretion was higher in the maltodextrin group (P = 0.004). Increased protein intake, at the expense of maltodextrin, lowers BP in overweight adults with upper-range prehypertension and grade 1 hypertension. This trial was registered at www.trialregister.nl as NTR 1362.

Abstract 16936: Vitamin D Supplementation Lowers Blood Pressure and Improves Control Rates in a Predominantly African American Hypertensive Cohort

Background: Vitamin D deficiency, highly prevalent in African Americans, has been associated with elevated blood pressure (BP) and hypertension in epidemiological studies. However, vitamin D supplementation has not been shown to consistently lower BP. Methods: Six hundred forty eight hypertensive patients with vitamin D blood levels and BP above JNC goal levels, with at least one follow-up visit, were followed a median of 10.6 months (5 clinic visits). At baseline, mean age was 56.5 years, mean BP 156/92 mm Hg, (mean of 22.3/8.8 mm Hg above JNC BP goal), mean vitamin D level 17.6 ng/ml; 67.2% were women and 87.7% were African American. Mixed effects general linear models were used to estimate longitudinal BP changes. Cox proportional hazards models were used to estimate the impact of vitamin D supplementation on first attainment of JNC goal BP. Repeated event proportional hazards analysis was utilized to determine the incremental (per 1 category higher of vitamin D supplementation) likelihood of attainment of JNC goal BP during follow-up. Models were adjusted for age, sex, initial BP level, baseline vitamin D level (&lt; 15, &gt; 15 ng/ml), antihypertensive drug therapeutic intensity, and vitamin D supplementation (0 = no vitamin D, 1 = &lt; 2000 IU/d, 2 = &gt; 2000 IU/d); the latter two variables were entered into the models as time-varying covariates. Results: Relative to no vitamin D supplementation, longitudinal SBP change was - 3.9 (p = 0.0089) and - 10.7 mm Hg (p = 0.0003) greater at incrementally higher vitamin D supplementation; DBP change was -2.5 (p = 0.0042) and - 7.0 mm Hg (p &lt; 0.0001) greater. Per 1 category higher vitamin D supplementation, there was no effect on first attainment of goal SBP HR = 1.15, 95% CI 0.94 - 1.39. However, first time DBP control was favorably impacted - HR = 1.28, 95% CI 1.09 - 1.50. Repeated events proportional hazards analysis showed greater BP control per 1 category higher vitamin D supplementation (SBP goal HR = 1.32, 95% CI 1.21 - 1.44; DBP goal HR =1.30, 95% CI 1.20 - 1.41). Conclusion: Vitamin D supplementation appears to lower BP and improve BP control rates independent of the intensity of antihypertensive treatment in a dose-dependent manner. The BP lowering effect is, however, most pronounced at &gt; 2000 IU/d.

Pomegranate juice supplementation lowers blood pressure but does not influence pulse wave velocity or antioxidant status in healthy young and middle-aged men and women

Pomegranate juice supplementation lowers blood pressure but does not influence pulse wave velocity or antioxidant status in healthy young and middle-aged men and women

Vitamin D and Hypertension

The prevalence of vitamin D insufficiency, defined by a 25-hydroxyvitamin D (25[OH]D) level <30 ng/mL, in the United States was 77% in 2004.1 Although the use of vitamin D supplementation may be increasing since 2004, it is likely that the majority of US citizens continue to have inadequate vitamin D status.2 Observational studies suggest that low 25(OH)D levels are associated with a higher risk of hypertension. However, findings from randomized trials of vitamin D supplementation to lower blood pressure are inconsistent, possibly stemming from variability in study population, sample size, vitamin D dose, and duration. If vitamin D supplementation lowers blood pressure, its widespread use could have major public health benefits. In this review, we summarize the existing literature dealing with the vitamin D-hypertension link, including mechanistic studies, observational data, and clinical trials; we place special emphasis on recent findings. Biological mechanisms relating vitamin D with hypertension have been proposed for >25 years. Vitamin D has been implicated in the proximal regulation of the renin-angiotensin system (RAS) and in interacting with the RAS to determine the intracellular calcium milieu in vascular smooth muscle. ### Vitamin D and the RAS Dietary sodium and increased activity of the RAS are known to contribute to hypertension; salt restriction and inhibition of RAS activity reduce blood pressure.3–5 Li et al6 provided convincing support for vitamin D as a proximal inhibitor of the RAS when they described a phenotype of excess plasma renin activity and hypertension in mice lacking the vitamin D receptor, which normalized after treatment with RAS antagonists. These vitamin D receptor–null mice also displayed an increased susceptibility to obstructive renal injury that could be prevented with RAS antagonism.7 Mice with deficient 1α-hydroxylase activity were also found to have increased plasma renin activity and hypertension, and this unfavorable phenotype could be reversed with 1,25-dihydroxyvitamin …

Inorganic Nitrate Supplementation Lowers Blood Pressure in Humans

Ingestion of dietary (inorganic) nitrate elevates circulating and tissue levels of nitrite via bioconversion in the entero-salivary circulation. In addition, nitrite is a potent vasodilator in humans, an effect thought to underlie the blood pressure-lowering effects of dietary nitrate (in the form of beetroot juice) ingestion. Whether inorganic nitrate underlies these effects and whether the effects of either naturally occurring dietary nitrate or inorganic nitrate supplementation are dose dependent remain uncertain. Using a randomized crossover study design, we show that nitrate supplementation (KNO(3) capsules: 4 versus 12 mmol [n=6] or 24 mmol of KNO(3) (1488 mg of nitrate) versus 24 mmol of KCl [n=20]) or vegetable intake (250 mL of beetroot juice [5.5 mmol nitrate] versus 250 mL of water [n=9]) causes dose-dependent elevation in plasma nitrite concentration and elevation of cGMP concentration with a consequent decrease in blood pressure in healthy volunteers. In addition, post hoc analysis demonstrates a sex difference in sensitivity to nitrate supplementation dependent on resting baseline blood pressure and plasma nitrite concentration, whereby blood pressure is decreased in male volunteers, with higher baseline blood pressure and lower plasma nitrite concentration but not in female volunteers. Our findings demonstrate dose-dependent decreases in blood pressure and vasoprotection after inorganic nitrate ingestion in the form of either supplementation or by dietary elevation. In addition, our post hoc analyses intimate sex differences in nitrate processing involving the entero-salivary circulation that are likely to be major contributing factors to the lower blood pressures and the vasoprotective phenotype of premenopausal women.

Scientific Opinion on the substantiation of health claims related to potassium and maintenance of normal muscular and neurological function (ID 320, 386) and maintenance of normal blood pressure (ID 321) pursuant to Article 13(1) of Regulation (EC) No 1924/2006

Scientific Opinion on the substantiation of health claims related to potassium and maintenance of normal muscular and neurological function (ID 320, 386) and maintenance of normal blood pressure (ID 321) pursuant to Article 13(1) of Regulation (EC) No 1924/2006

Soybean Protein Lowers Blood Pressure

Results from observational studies have suggested that soybean protein supplementation lowers blood pressure. Now, researchers in China have tested

Dietary vitamin E supplementation lowers blood pressure in spontaneously hypertensive rats.

In spontaneously hypertensive rats (SHRs) excess endogenous aldehydes bind sulfhydryl groups of membrane proteins, altering membrane Ca2+ channels and increasing cytosolic free calcium and blood pressure. The thiol compound, N-acetyl cysteine, normalizes elevated blood pressure in SHRs by binding excess endogenous aldehydes. Vitamin E increases tissue glutathione levels--a storage form of cysteine. The aim of the present study was to investigate whether a dietary supplementation of vitamin E lowers blood pressure and prevents renal vascular changes by normalizing tissue aldehyde conjugates and cytosolic [Ca2+] in SHRs. Starting at 12 weeks of age, animals were divided into three groups of six animals each. Animals in the WKY-control group and SHR-control group were given a normal diet and the SHR-vitamin E group a diet supplemented with vitamin E (34 mg/ kg feed) for the next 9 weeks. After 9 weeks, systolic blood pressure, platelet [Ca2+]i, and liver, kidney and aortic aldehyde conjugates were significantly higher in SHR controls as compared to WKY controls and the SHR-vitamin E group. SHR-controls also showed smooth muscle cell hyperplasia in the small arteries and arterioles of the kidney. Dietary vitamin E supplementation in SHRs lowered the systolic blood pressure, cytosolic [Ca2+], tissue aldehyde conjugates and attenuated adverse renal vascular changes.

A Polyunsaturated Fatty Acid Diet Lowers Blood Pressure and Improves Antioxidant Status in Spontaneously Hypertensive Rats

gamma-Linolenic acid [GLA, 18:3(n-6)], eicosapentaenoic acid [EPA, 20:5(n-3)] and docosahexaenoic acid [DHA, 22:6(n-3)] have been reported to prevent cardiovascular diseases. However, they are highly unsaturated and therefore more sensitive to oxidation damage. We investigated the effects of a diet rich in these polyunsaturated fatty acids (PUFA) on blood pressure, plasma and lipoprotein lipid concentrations, total antioxidant status, lipid peroxidation and platelet function in spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto rats (WKY). Five-week-old SHR and WKY rats were fed for 10 wk either a diet containing Isio 4 oil or a diet rich in GLA, EPA and DHA (5.65, 6.39 and 4.94 g/kg dry diet, respectively). The total antioxidant status was assayed by monitoring the rate of free radical-induced hemolysis. VLDL-LDL sensitivity to copper-induced lipid peroxidation was determined as the production of thiobarbituric acid reactive substances. After dietary PUFA supplementation, a significant decrease in blood pressure of SHR rats (-20 mm Hg) was observed and the total antioxidant status was enhanced. VLDL-LDL resistance to copper-induced peroxidation was increased in both strains. The PUFA supplementation did not change platelet maximum aggregation in SHR rats, but it decreased the aggregation speed. In hypertensive rats, GLA + EPA + DHA supplementation lowers blood pressure, enhances total anti-oxidant status and resistance to lipid peroxidation, diminishes platelet aggregation speed and lowers plasma lipid concentrations. Thus, it enhances protection against cardiovascular diseases. Therefore, nutritional recommendations for cardiovascular disease prevention should take into account the pharmacologic properties of GLA, EPA and DHA.

MECHANISM OF ANTIHYPERTENSIVE EFFECT OF DIETARY POTASSIUM IN EXPERIMENTAL VOLUME EXPANDED HYPERTENSION IN RATS

Dietary potassium supplementation lowers blood pressure (BP) and attenuates complications in hypertensive subjects, particularly those with the low renin volume expanded (LRVE) variety. We and others have shown that the plasma level of a digitalis like substance (DLS) is elevated in this type of hypertension. We therefore, examined the effect of increases in dietary potassium on the plasma level of endogenous DLS, myocardial and renal Na+, K+-ATPase (NKA) activities, BP, and renal excretory function in reduced renal mass (RRM)-salt hypertension in the rat, a classical model of LRVE hypertension. 70% RRM rats were divided in 4 groups, namely those consuming: 1) a sodium free and normal potassium (1.3% as KCl) diet (RRM-0 Na), 2) a normal sodium and normal potassium diet (RRM-NaK), 3) a normal sodium and high potassium (2 X normal) diet (RRM-Na2K), and 4) a normal sodium and 4 times normal potassium diet (RRM-Na4K). At the end of 4 weeks of dietary treatment, direct BP was recorded, plasma level of DLS determined by bioassay and with a radioimmunoassay for digoxin (DIF) and myocardial and renal NKA activities were measured. As expected, compared to RRM-0Na rats, RRM-NaK rats developed hypertension. BP increased significantly less in RRM-Na2K, whereas BP did not increase in RRM-Na4K rats. Hypertension in RRM-NaK rats was associated with an increase in plasma DLS and DIF and decrease in renal and myocardial NKA activities. DLS was increased (DIF was not changed) and myocardial NKA also decreased in rats consuming double potassium. However, quadrupling potassium in the diet (RRM-Na4K) normalized DLS and DIF and increased myocardial and renal NKA activities, compared to RRM-0Na rats. Also compared to RRM-0Na, water consumption, urinary volume excretion, sodium, and potassium increased in the other 3 groups, more so in RRM-Na4K rats. These data show that quadrupling the potassium in the diet prevents the BP increase in RRM rats and this is associated with diuresis/natriuresis and normalization of DLS, perhaps because the diuresis/natriuresis normalizes blood volume.